Generally, the industry of semiconductor manufacturing involves highly complex techniques for fabricating integrating circuits using semiconductor materials which are layered and patterned onto a substrate, such as silicon. An integrated circuit is typically fabricated from a plurality of reticles. Initially, circuit designers provide circuit pattern data, which describes a particular integrated circuit (IC) design, to a reticle production system, which transforms the pattern data into a plurality of reticles. One emerging type of reticle is an extreme ultraviolet (EUV) reticle that is comprised of a plurality of mostly reflecting layers and a patterned absorber layer.
Due to the large scale of circuit integration and the decreasing size of semiconductor devices, the reticles and fabricated devices have become increasingly sensitive to critical dimension (CD) uniformity variations. These variations, if uncorrected, can cause the final device to fail to meet the desired performance due to electrical timing errors. Even worse, they can cause final device to malfunction and adversely affect yield.
It would be beneficial to provide techniques that are suitable for inspecting and measuring EUV reticles to monitor CD uniformity.